opt - LLVM optimizer — LLVM 22.1.3 documentation

# opt - LLVM optimizer

## SYNOPSIS

opt [options] [filename]

## DESCRIPTION

The opt command is the modular LLVM optimizer and analyzer. It takes LLVM source files as input, runs the specified optimizations or analyses on it, and then outputs the optimized file. The optimizations available via opt depend upon what libraries were linked into it as well as any additional libraries that have been loaded with the `-load` option. Use the `-help` option to determine what optimizations you can use.

If `filename` is omitted from the command line or is “`-`”, opt reads its input from standard input. Inputs can be in either the LLVM assembly language format (`.ll`) or the LLVM bitcode format (`.bc`).

If an output filename is not specified with the `-o` option, opt writes its output to the standard output.

## OPTIONS

-f

  Enable binary output on terminals. Normally, opt will refuse to write raw bitcode output if the output stream is a terminal. With this option, opt will write raw bitcode regardless of the output device.

-help

  Print a summary of command line options.

-o <filename>

  Specify the output filename.

-S

  Write output in LLVM intermediate language (instead of bitcode).

-passes=<string>

  A textual (comma-separated) description of the pass pipeline, e.g., `-passes="sroa,instcombine"`. See invoking opt for more details on the pass pipeline syntax.

-strip-debug

  This option causes opt to strip debug information from the module before applying other optimizations. It is essentially the same as -strip but it ensures that stripping of debug information is done first.

-verify-each

  This option causes opt to add a verify pass after every pass otherwise specified on the command line (including -verify). This is useful for cases where it is suspected that a pass is creating an invalid module but it is not clear which pass is doing it.

-stats

  Print statistics.

--save-stats, --save-stats=cwd, --save-stats=obj

  Save LLVM statistics to a file in the current directory (`--save-stats`/”–save-stats=cwd”) or the directory of the output file (”–save-stats=obj”) in JSON format.

-time-passes

  Record the amount of time needed for each pass and print it to standard error.

-debug

  If this is a debug build, this option will enable debug printouts from passes which use the `LLVM_DEBUG()` macro. See the LLVM Programmer’s Manual, section `#DEBUG` for more information.

-load=<plugin>

  Load the dynamic object `plugin`. This object should register new optimization or analysis passes. Once loaded, the object will add new command line options to enable various optimizations or analyses. To see the new complete list of optimizations, use the `-help` and `-load` options together. For example:

      opt -load=plugin.so -help

-print-passes

  Print all available passes and exit.

## EXIT STATUS

If opt succeeds, it will exit with 0. Otherwise, if an error occurs, it will exit with a non-zero value.